1. Field of the Invention
The present invention generally relates to an apparatus and method for cutting target material. The present invention more particularly relates to an apparatus and method for cutting target material of a substantial thickness using a thermite based charge.
2. Description of the Prior Art
A number of devices for cutting materials of a substantial thickness are known in the art. Many of these devices employ explosive shaped charges which deliver energy to the surface of a material in the form of a high pressure, high velocity shock front. The conical or "V" shaped charge, for example, explodes and focuses cutting energy onto the surface of the material to be cut. A primary disadvantage of explosive shaped charges is that they generate excessive noise and debris upon detonation. This noise and debris can pose potentially serious health and safety hazards to someone using a cutting device which employs conventional shaped charge explosives.
Thermite-based cutting devices which employ a cutting flame produce virtually no extended shock wave and generate relatively little over pressure. Thermite-based cutting devices do not present the same health and safety hazards which are attendant upon explosive shape charge cutting devices.
U.S. Pat. No. 2,587,243 discloses an apparatus for producing a gaseous penetrating jet for cutting materials or objects. This patent uses a chemical charge which, when detonated, ruptures a means interposed along the path of the generated high velocity gases. The means converges upon rupture and causes a material placed beneath the apparatus to be cut by the resultant high velocity gas explosion.
U.S. Pat. No. 4,693,181 discloses a linear cutting charge device including an explosive mass formed in the shape of a bar. Detonation of the charge in this patent is disclosed as stating that it compresses a metal liner and converts the metal liner into an outwardly projected slug of metal, the shape of which is dependent upon the shape of a cavity of the device. It is this outwardly projected slug which penetrates the work surface of a material which is cut or deformed by the detonation and subsequent penetration.
U.S. Pat. No. 4,815,384 discloses a device with a housing for use with joinable or interconnectable cutting charges. The stated purpose of this patent is to avoid formation of a saw-tooth cutting profile on a target work surface acted upon by the device discussed in the patent.
What has not been disclosed in the prior art, however, is use of a thermitebased apparatus for directing or focusing a cutting flame derived from the activation of a thermite charge for the purpose of cutting substantially thick material such as steel plates and bars, for example. In addition, the prior art has not provided a practical solution for effecting an extended, linear cut in a piece of material. The prior art also has not sufficiently addressed concerns related to the health and safety of a user using an explosive shape charge apparatus to create high velocity explosions to cut material. As a result, the prior art has also not adequately considered use of a thermite-based cutting apparatus to alleviate hazards associated with debris, noise and pressure waves generated from using explosive charges to cut material having a substantial thickness.
In spite of the foregoing known apparatus and methods for cutting material, there remains a real and substantial need for an apparatus for cutting material which employs a thermite-based charge to ensure a safe and efficient cutting action.